The Research And Optimization Design Of Frame Steel Structure

As the steel structure is used in our country more and more broadly, it is realistic economical to make the best design because of the flaws that existing in the present design method and raising of steel price. The steel structure frame system has extensive application, especially in the industry workshop and the civil construction. At present, the design of frame steel structure generally use trial-and-error method: first, define the primary parameter (structure arrangement and section types of various components), then, choose the section size according to restriction conditions. It may be used as the final scheme after making proper correction according to structure calculation. As a result, it often leads the quantity of steel increase. In the design process of frame steel structure, the engineering design optimization problem can be solved quickly and effectively with the help of the present optimization design theory and computer technology.The domestic and foreign scholars have done a lot of work about the theory and method of structure optimization design. But few of them could be applied in the project, specially regarding space frame steel structure. Based on the structure optimization algorithm of full stress design, a six stories frame steel structure of an automobile exhibition in Wuhan is carried on the optimization design with the help of finite element analysis software and re-development.First, the frame steel structure design theory including the second-order elastic analysis method and the second-order elastoplasticity analysis method is introduced. The second-order elastic analysis short-cut method that the design standard uses is simple, but it is unable to consider the influence of the second-order effects precisely. The higher analytic method is too complex to apply in practice project.Then, in view of frame steel structure and based on the project example in this paper, the computational method and principle of steel structure composite floor are summarized, as well as the calculation principle and considerations of the node design.At last, the ANSYS finite element model is established to simulate the structure stress characteristic of four kinds of load operating in the states of ultimate bearing capacity and normal using. Using the APDL parametrization language programming, the project in this paper under different operating modes is optimized, with the least steel weight per unit area as the objective function, with section size of components as design variables, with strength, rigidity and structural requirements as state variables.The result indicated that this method could save the steel quantity about 6.645% and the economic efficiency is obvious. After the optimization, the structure still has certain safety margin, so the optimized result is reliable and the optimized purpose is realized. Then this method could be promoted in the optimal design of frame steel structure. The precision of first-order optimized method is high, and the statistical analysis of the design variables could be available. But the zeroth order method is recommended when applied in the project because the first-order optimized method takes too much time.